Chemical methods will be developed for the preparation of eight classes of nucleosides that are so designed as to a) undergo neighboring-group displacement or elimination reactions in vivo to liberate anti-cancer agents, or b) to undergo in vivo enzymatic cleavage in tumor tissues rich in Beta-glucuronidase to liberate potent drugs. "In house" biochemical and biological collaborative studies for proper evaluation of the masked precursor nucleosides to be synthesized are described briefly, as well as preliminary data from on-going studies. From these studies, structure-activity relationships should be forthcoming to relate chemical or enzymatic structural transformations in vivo with biological activity, and thus aid in the development of new agents superior to those drugs currently available for the treatment of cancer in man. Practical chemical synthesis of 2-halogeno-D-arabinofuranosyl sugars and of nucleosides thereof will be developed. The syntheses of Beta-(1" yields 5')- glucuronides of nucleosides will be investigated along with the synthesis of disaccharides of 5-Beta-D-glucopyranosyluronic acid-ribofuranoses. Chemical transformations of anhydronucleosides will be further investigated.